1. Field of the Invention
This invention concerns liquid level indicators and more particularly liquid level indicators of the type providing a visual indication of the level of a liquid in a dishwasher door-mounted dispenser tank whenever it is at or above a predetermined level, usually at a level approaching empty.
2. Background of the Invention
It is common practice in the design of modern dishwashing machines to provide liquid dispenser tanks for dispensing automatically rinse aid liquids to prevent the spotting of dishes for the installation of these tanks is within the inner and outer door panels of the dischwasher door since this is convenient space to hold the tank and also provides convenient access for refilling of a tank when the door is in the open position.
A problem inherent in this location is in readily determining the level of liquid within the tank, such that the user may so determine the level without the need to check by dipstick when the level within the tank is approaching empty.
One difficulty arising from the installation within the door involves the inaccessibility of the dispenser, since the tank is confined within the door panels. The inner panel is not available for viewing when the door is in the closed position, while the outer door panel is preferably free from any functional features, as the aesthetic qualities of the front exterior of the machine would be somewhat compromised.
Accordingly, it has been deemed necessary to attempt to determine the level of liquid within the tank when the tank is in the horizontal position with the dishwasher door open. However, in this position, the liquid has retreated from the side adjacent the inner panel and has redistributed itself against the opposite wall which becomes the bottom of the tank, i.e., the sidewall of the tank adjacent the outer door panel. Since this is remote from the inner door panel, a sight glass device is impossible in this situation, requiring that any viewing device to directly view the liquid level in the tank extend into the tank and accordingly be required to depend on ambient light within the tank for viewing of the liquid level.
This latter requirement creates difficulty due to the lack of light in the space between the door panels for easy reading of any viewing device which attempts to view the liquid within the tank, such as is disclosed in U.S. Pat. No. 3,152,723.
This patent discloses the use of an indicator knob which also serves as a filler spout cap having a stem portion extending into the tank and adapted to provide a visual indication when the tank liquid level declines below that at the stem end. Since this approach depends on the light level within the tank to provide the visible indication, it would not afford a highly visible indication.
While any number of elaborate and exotic devices might easily afford a proper indication, an additional constraint applied in the design of such devices intended for incorporation into home appliances is that they be simple and low in cost in keeping with the relatively low selling prices of such appliances.
In application, Ser. No. 852,118, filed Nov. 16, 1977, assigned to the assignee of the present application, there is disclosed a simple low cost device for a dishwasher dispenser tank. In this device, there is provided an arrangement for the capture of a small quantity of the tank liquid if an adequate level of liquid is present in the tank and its retention as the diswasher door is opened. A viewing chamber is provided within an indicator housing extending through the inner door panel, with a sight window allowing observation of the contents of the viewing chamber such that it may be directly viewed from the exterior above the inner door with the ambient room light level affording ready viewing of the quantity of liquid so captured. However, the embodiment disclosed in that application requires redesign of the inner door panel and/or the dispenser tank, and involves an additional opening in the inner door panel.
It is therefore an object of the present invention to provide an indicator device which provides such a direct viewing of a quantity of dispensed liquid within a movable dispenser tank, which quantity of liquid is captured from the liquid within the tank and disposed within a viewing chamber which may be viewed in direct ambient light, but which does not require extensive redesign of the tank or inner panel, and does not necessitate an additional opening in the inner panel.
It is another object of the present invention to provide such a liquid level indicator device which is simple, low in cost and yet provides an effective indication of the liquid level in the dispensing tank whenever the level is at or above a predetermined tank level approaching empty.